In a manufacturing process of a semiconductor device or a flat panel such as a liquid crystal display, a desired microscopic structure (e.g., holes, trenches, or the like) pattern is formed on a substrate such as a semiconductor wafer or a FPD substrate by performing various processes such as a film forming process and an etching process on the substrate. Recently, the semiconductor device tends to be highly integrated year by year. To meet a demand for miniaturization of patterns formed on the substrate, improvement in resist materials or exposure technology has been sought for and, thus, dimensions of an opening of a resist pattern are getting finer.
Along with the miniaturization of the semiconductor device, there has occurred a problem that when an etching target film on a substrate is etched by using a resist pattern as a mask, dimensions of the opening of the resist pattern may be enlarged or a sidewall of a recess in the etching target film may be overetched, resulting in a deviation of a critical dimension (CD) of a hole or a trench from a target value and a failure to obtain designed device characteristics.
Recently, as a solution to this problem, various researches have been conducted to develop a technique for preventing a deviation of a critical dimension of a pattern formed on an etching target film from a target value or to develop a technique for forming a pattern of an opening dimension smaller than an opening dimension of the resist pattern on an etching target film. In such techniques, an etching process is performed after reducing the opening dimension of the resist pattern by performing a deposition process for depositing a deposit on the resist pattern by supplying, e.g., a CHF-based processing gas (see, for example, Patent Documents 1 and 2).
Patent Document 1: Japanese Patent Laid-open Publication No. 2007-194284    Patent Document 2: Japanese Patent Laid-open Publication No. 2007-273866
In the deposition process, a deposit may be uniformly and effectively deposited on a sidewall of an opening of the resist pattern by increasing radical density. To increase the radical density, it may be desirable to supply a processing gas after increasing an internal pressure of a processing chamber to, e.g., about 100 mTorr or higher.
In the deposition process, however, as the internal pressure of the processing chamber increases, critical dimensions of patterns formed after the etching was observed to become non-uniform. As the internal pressure of the processing chamber increases, dissociation of the processing gas may be facilitated, and, thus, a difference in dissociation degree of the processing gas may be generated in a diametric direction of the substrate, which in turn may cause non-uniformity in deposition degree on the surface of the substrate. Thus, the non-uniformity in the critical dimensions of the patterns on the substrate is deemed to be caused by such non-uniformity in the deposition degree on the surface of the substrate. Although the non-uniformity of the critical dimensions is in the order of nanometer (nm), such a slight degree of non-uniformity may not be regarded negligible to meet a demand for further miniaturization of the patterns.